Rigorous comparative study of energy-integrated distillation schemes

This paper presents results of a rigorous study and comparison of conventional and energy-integrated distillation schemes for the separation of ternary mixtures. The major part of this work is devoted to the design and simulation of the fully thermally coupled distillation column (Petlyuk or Kaibel column) with particular emphasis on the question of the fractional recovery of the middle component in the prefractionator and as a consequence the internal recycle streams. A comparative economic parametric study is carried out for three different distillation schemes: conventional sequences, heat-integrated columns, and the fully thermally coupled distillation column. The heat-integrated columns show the best economic features over the other two schemes except the few cases when the concentration of the middle component in the feed is high and the A/B split is more difficult than the B/C split. In such rare cases the fully thermally coupled distillation column proves to be the cheapest solution. In the cases of sharp separations the heat-integrated scheme is always the most economical solution.